Question

What happens when an universal indicator is added to amphoteric oxides?

Answer 1

ZnO when added to HCl solution acts like a base

So it can change the red colour of HCl solution having universal indicator or litmus indicator into a blue colour solution.

But ZnO when added to NaOH solution turns it into red coloured solution when tested with litmus or universal indicator solution . Because at that time ,ZnO acts like an acid